The present invention relates to an adjusting method for a position detecting apparatus which detects the position or the like of a to-be-detected mark by receiving a flux of light from the to-be-detected mark, and is suitable for use in adjusting an alignment sensor provided in an exposure system that is used in a lithography process for forming a fine pattern of, for example, a semiconductor integrated circuit, an image pickup device (CCD or the like), a liquid crystal display or a thin film magnetic head or the like, or an overlay error measuring apparatus or the like for measuring an error in overlaying a plurality of layers on a substrate. This application is a continuation application based on PCT/JP99/00551 designating U.S.A.
In manufacturing semiconductor integrated circuits, use is made of a projection aligner (stepper or the like) which transfers the image of a pattern of a reticle used as a mask onto the shot areas on a wafer (or a glass plate or the like) on which a photoresist has been applied. For example, a semiconductor integrated circuit is formed by overlaying several tens of layers of circuit patterns on a wafer in a predetermined positional relationship. When, for example, the circuit patterns of the second and subsequent layers are projection-transferred onto the wafer, therefore, it is necessary to maintain, with high precision the alignment between the circuit patterns (existing patterns) that have been formed in the individual shot areas on the wafer in the preceding processes with the image of a pattern of the reticle to be exposed next. The projection aligner is therefore equipped with an alignment sensor which detects the position of alignment marks (wafer marks) provided in each shot area on the wafer together with the circuit pattern.
While there are various types of alignment sensors, an image-forming type (image processing type) which is unlikely to be affected by asymmetry of the wafer marks has become widespread recently. This type has an optical system with a similar structure to that of a microscope, picks up the image of a wafer mark magnified by an objective lens using an image pickup device and detects the position of that wafer mark from the image signal.
Further, an overlaying error measuring apparatus (registration measuring apparatus) is used to check the precision of overlaying of a pattern which has undergone overlaying exposure by the projection aligner on the existing patterns. While a position detecting apparatus provided in the overlaying error measuring apparatus is also an optical system similar to the image-forming type alignment sensor equipped in the exposure system, the target for measurement is the amount of misregistration between the relative positions of an underlying mark (existing mark) and an overlaying mark (new mark), not the position of a single wafer mark (absolute position).
If there remains an error in the optical characteristics of the optical system of the alignment sensor or the position detecting apparatus in the overlaying error measuring apparatus, i.e., an aberration (coma or the like) of the detecting optical system of an image-forming system or the like, or an adjustment error of the illumination system (misregistration of the aperture stop of the illumination system), the error in the optical characteristics produces an error in the detected position. This error is generally called TIS (Tool Induced Shift) because it originates from a tool.
With regard to this, there has recently been proposed a method of adjusting the optical system of a position detecting apparatus to reduce the TIS based on the measured value of the distance between two types of recessed and protruding marks (step marks) having different amounts of steps (hereinafter, this method will be called xe2x80x9cdifferent step mark methodxe2x80x9d). This different step mark method is disclosed in, for example, T. Kanda, K. Mishima, E. Murakami and H. Ina: Proc. SPIE, Vol. 3051, pp. 846-855 (1997). Specifically, the method measures a distance D1 between two recessed and protruding marks having different amounts of steps on a wafer, turns the wafer 180xc2x0 and then measures a distance D2 between those two recessed and protruding marks again. In this case, the TIS is half the difference between the measured value at a rotational angle of 0xc2x0 and the measured value at a rotational angle of 180xc2x0, i.e., (D1xe2x88x92D2)/2, and the optical system is adjusted in such a way that this TIS falls within an allowable range.
The overlaying error measuring apparatus often has a box-in-box mark, which comprises a mark on the outer frame and a mark on the inner frame, as measuring targets. Given that the amount of two-dimensional misregistration of the center of the inner frame mark which is measured with respect to the center of the outer frame mark on a substrate for evaluation is (xcex94X1, xcex94Y1) and the amount of two-dimensional misregistration of the centers of both marks which is acquired through remeasurement after the wafer is turned 180xc2x0 is (xcex94X2, xcex94Y2), (Ta, Tb), the TIS of the overlaying error measuring apparatus becomes ((xcex94X1+xcex94X2)/2, (xcex94Y1+xcex94Y2)/2). In this case, the optical system is also adjusted in such a way that (Ta, Tb) as the TIS falls within an allowable range.
Conventionally, as described above, the different step mark method has been proposed to correct TIS which is a tool-induced error of the position detecting apparatus. However, the different step mark method has the disadvantage that it is difficult to accurately form two types of recessed and protruding marks, set to have predetermined steps, close to each other while the amounts of their steps are different from each other.
Even if it is possible to accurately form recessed and protruding marks with different steps, the different step mark method may be unable to adjust for the aberration of the detecting optical system with high precision even though it is effective in adjusting the position of the aperture stop of the illumination system.
Further, to correct the TIS, conventionally, after the distance or the relative misregistration between a pair of marks for evaluation on a predetermined substrate is measured, the substrate is turned 180xc2x0 and the distance or the relative misregistration between the pair of marks is measured again to acquire the TIS. This disadvantageously increases the time required for the measuring operation. Normally, after the TIS is acquired in this manner and a predetermined optical member is adjusted, it is necessary to perform an operation of turning the substrate 180xc2x0 and taking a measurement, and an operation of adjusting the predetermined optical member until the TIS actually falls within the allowable range. This brings about such disadvantages that the time needed for the measurement and adjustment becomes extremely long and when the rotational angle of the substrate cannot be set exactly to 180xc2x0, a measuring error remains.
Further, provision of a rotary stage which can turn the substrate 180xc2x0 on a stage where the substrate is to be placed complicates and enlarges the structure of the stage, and is therefore not practical. If the substrate is temporarily removed from the stage after measuring the distance or the like between a pair of marks on the substrate on the stage and then the substrate is turned 180xc2x0 and placed again on the stage, foreign matter may adhere to the substrate and the work of placing and removing the substrate is troublesome.
Further, conventionally, after the distance between two marks with different steps is detected, those marks are turned 180xc2x0, the distance is measured again and the difference between the two detected distances is taken as the TIS. This means that the average value of the results of the two detections of the distances is considered as a reference value (true value) of the distance between the two marks with different steps. When such two marks with different steps are turned 180xc2x0, however, the shapes of the marks as a whole are changed so that an error other than TIS, such as distortion, may enter the results of the distance detections.
In view of the above, it is a first object of this invention to provide an adjusting method for a position detecting apparatus, which can easily and accurately form the necessary marks for measuring the optical characteristics of the optical system.
Further, it is a second object of this invention to provide an adjusting method for a position detecting apparatus, which can accurately form necessary marks for measuring the optical characteristics of the optical system and correct a predetermined aberration of a detecting optical system or an adjustment error of an illumination system with high precision.
It is a third object of this invention to provide an adjusting method for an optical system, which can measure a tool-induced error (TIS) in a short period of time and with high accuracy.
Further, it is a fourth object of this invention to provide a substrate for evaluation which can be used in implementing the aforementioned adjusting methods.
It is a fifth object of this invention to provide an adjusting method for a position detecting apparatus, which can correct a tool-induced error (TIS) with high accuracy.
Further, it is a sixth object of this invention to provide an adjusting method for a position detecting apparatus which can accurately form the necessary marks for measuring the optical characteristics and correct a predetermined aberration of a detecting optical system or an adjustment error of an illumination system with high precision.
Furthermore, it is a seventh object of this invention to provide a position detecting apparatus or a pattern detecting apparatus which can employ such adjusting methods.
It is also an object of this invention to provide an exposure system equipped with the position detecting apparatus, a method of manufacturing such an exposure system, and a method of fabricating a device, which uses the aforementioned adjusting methods.
A first adjusting method for a position detecting apparatus according to this invention, which is equipped with a detecting optical system (10, 9, 12, 15, 16, 21) for condensing a flux of light from one to-be-detected mark or a plurality of to-be-detected marks, for detecting a position of the one to-be-detected mark or relative positions of the plurality of to-be-detected marks based on the flux of light condensed by the detecting optical system, is designed in such a way that a plurality of lattice marks (DM1, DM2) each having recesses (31a, 32a) and projections (31b, 32b) alternately and periodically provided in a predetermined measuring direction and having different ratios of the width of the recesses to the width of the projections are formed on a predetermined substrate (11) in the vicinity of one another, and measuring the distance (Md) between the plurality of lattice marks (DM1, DM2) in the measuring direction through the detecting optical system, and adjusting predetermined optical characteristic of the detecting optical system based on the measured value.
According to this invention, for example, a first lattice mark (DM1) which has recesses (31a) having a width a and projections (31b) having a width b periodically provided and a second lattice mark (DM2) which has recesses (32a) having a width c and projections (32b) having a width d periodically provided are used as marks for measuring the optical characteristics of the detecting optical system. At this time, the ratio of the width of the recesses of the first lattice mark (DM1) to the width of the projections (a:b or a/b) differs from the ratio of the width of the recesses of the second lattice mark (DM2) to the width of the projections (c:d or c/d). Note that the duty ratio with respect to one pitch of the recesses (31a) is 100xc3x97a/(a+b) (%), and the duty ratio with respect to one pitch of the recesses (32a) is 100xc3x97c/(c+d) (%), which are different. According to this invention, a plurality of lattice marks can have substantially the same step height but should be different from one another in the ratio of the width of the recesses to the width of the projections. It is therefore possible to easily and accurately form the lattice marks in a normal lithography process by using a mask on which a plurality of master patterns which have different ratios of the light shielding section to the light transmitting section are formed.
Because this invention uses a plurality of lattice marks having different ratios of the width of the recesses to the width of the projections and thus different duty ratios which express the ratio of the width of the recesses (or projections) with respect to one pitch as percentages, this adjusting method can be called the xe2x80x9cdifferent ratio mark methodxe2x80x9d. In this case, if an asymmetrical aberration, such as coma, remains in the detecting optical system, the position of each mark image shifts in accordance with the duty ratio. Through measurement of the distance between the individual mark images, therefore, the measured distance between the individual mark images is shifted from the reference value (designed value or the like) when an asymmetrical aberration remains, and it agrees with the reference value when the asymmetrical aberration is not existed. By measuring the distance between the individual mark images and adjusting the optical characteristics in such a way that the measured value becomes the reference value by utilizing the above, an asymmetrical aberration can easily be et within an allowable range.
It is desirable that the ratio of the width of the recesses of one of the plurality of lattice marks (DM1, DM2) to the width of the projections should be 1:1. Because the image of a mark whose ratio of the width of the recesses to the width of the projections is 1:1 has very little transverse shift caused by asymmetrical aberrations, it can be used as a reference mark at the time of comparing distances.
One example of the detecting optical system is an image-forming optical system that projects images of the plurality of lattice marks onto a predetermined observation surface and one example of the optical characteristic of the detecting optical system to be adjusted is coma. As the distance between those mark images varies in high accuracy to comas, comas can be corrected with high precision.
A second adjusting method for a position detecting apparatus according to this invention, which is equipped with an illumination system (1-8) for illuminating one to-be-detected mark or a plurality of to-be-detected marks and a detecting optical system (10, 9, 12, 15, 16, 21) for condensing a flux of light from the to-be-detected marks, for detecting the position of the one tobe-detected mark or the relative positions of the plurality of to-be-detected marks based on the flux of light condensed by the detecting optical system, is designed in such a way that two lattice marks (HM1, HM2) each having recesses (33a, 35b) and projections (33b, 35a) alternately and periodically provided in a predetermined measuring direction and having such shapes that the recesses and the projections of one of the lattice marks (HM1, HM2) are the inverse of those of the other lattice marks are formed on a predetermined substrate (11) in the vicinity of each other, and measuring the distance between the two lattice marks in the measuring direction through the detecting optical system, and adjusting a predetermined optical characteristic of the illumination system based on the measured value.
According to this invention, given that the width of the recesses (33a) of the first lattice mark (HM1) in those lattice marks is narrower than the width of the projections (33b), a darklevel image of a dark level is acquired at, for example, the recesses (33a). Accordingly, the width of the projections (35a) of the second lattice mark (HM2) becomes narrower than the width of the recesses (35b), and a dark-level image of a dark level is acquired at the projections (35a). That is, there is produced a step at the portion in the first lattice mark (HM1) and the second lattice mark (HM2) where a dark-level image is obtained. If there is an adjustment error of the illumination system, such as misregistration of the aperture stop, or an uneven illuminance distribution at the location of the aperture stop, the distance between the images of those two lattice marks is shifted, so that the adjustment error of the illumination system can be corrected by adjusting that distance in such a way as to reach a predetermined reference value. In this case too, those lattice marks can be formed easily and accurately by using a predetermined mask.
In this case, one example of the optical characteristic of the illumination system to be adjusted is the position in the plane perpendicular to the optical axis of the aperture stop (3) in the illumination system.
Further, in the above-described second adjusting method, with the two lattice marks (HM1, HM2) on the substrate (11) being first lattice marks, two second lattice marks (DM1, DM2) each having recesses and projections alternately and periodically provided in the measuring direction and having different ratios of the width of the recesses to the width of the projections may be formed on the substrate in the vicinity of each other, and after the predetermined optical characteristic of the illumination system is adjusted based on the distance between the first lattice marks (HM1, HM2), the distance between the second lattice marks (DM1, DM2) in the measuring direction may be measured through the detecting optical system, and a predetermined optical characteristic of the detecting optical system may be adjusted based on the measured value.
This combines the use of the second adjusting method and the first adjusting method (different ratio mark method) of this invention. At this time, the adjustment of the predetermined optical characteristic of the illumination system which uses the first lattice marks (HM1, HM2) is not affected by an aberration of the detecting optical system. Accordingly, the illumination system is adjusted first by using the first lattice marks (HM1, HM2), and then an asymmetrical aberration of, for example, the image-forming optical system is adjusted by the different ratio mark method (first adjusting method) so that both can be adjusted independently, which is convenient.
It is desirable that in the aforementioned first or second adjusting method, the plurality of lattice marks (DM1, DM2; HM1, HM2) should be formed in series in the measuring direction on the substrate and close to one another. This can ensure high-precision measurement of the distance between those mark images in the measuring direction without a so-called Abbe error and ensure high-precision correction of an optical error. Further, it is desirable that the steps of the recesses (31a, 32a; 33a, 35b) and the steps of the projections (31b, 32b; 33b, 35a) substantially lie within a range of 40 to 60 nm. This can provide a high-contrast image so that the distance between a plurality of marks can be detected with high precision.
A first position detecting apparatus according to this invention, which is equipped with a detecting optical system (10, 9, 12, 15, 16, 21) that condenses a flux of light from one to-be-detected mark or a plurality of to-be-detected marks and a photoelectric detector (22) that receives the flux of light condensed by the detecting optical system, which detects the position of the one to-be-detected mark or relative positions of the plurality of to-be-detected marks based on a detection signal from the photoelectric detector, comprises a positioning member (16a, 16b, 17a, 17b), which is connected to the detecting optical system, and which positions at least a part of the optical member (16) in the detecting optical system which affects a predetermined optical characteristic (e.g., within a plane perpendicular to the optical axis of the detecting optical system), and a control operation system (23), which is electrically connected to the positioning member, and which drives the positioning member in order to reduce an error in the predetermined optical characteristics based on the distance between a plurality of predetermined lattice marks with respect to a predetermined measuring direction, which is detected through the detecting optical system and the photoelectric detector. According to this invention, the first adjusting method for a position detecting apparatus of this invention can be used.
A second position detecting apparatus according to this invention, which is equipped with an illumination system (1-8) that illuminates one to-be-detected mark or a plurality of to-be-detected marks, a detecting optical system (10, 9, 12, 15, 16, 21) that condenses a flux of light from the to-be-detected marks, and a photoelectric detector (22) that receives the flux of light condensed by the detecting optical system, which detects the position of the one to-be-detected mark or relative positions of the plurality of to-be-detected marks based on a detection signal from the photoelectric detector, comprises a positioning member (4a, 4b, 5a, 5b), which is connected to the illumination system, and which positions at least a part of the optical member (3) in the illumination system which affects a predetermined optical characteristic (e.g., within a plane perpendicular to the optical axis of the illumination system), and a control operation system (23), which is electrically connected to the positioning member, and which drives the positioning member in order to reduce an error in the predetermined optical characteristic based on the distance between predetermined plural lattice marks with respect to a predetermined measuring direction, which is detected through the detecting optical system and the photoelectric detector. According to this invention, the second adjusting method for a position detecting apparatus of this invention can be used.
An optical-system adjusting method according to this invention, which adjusts a predetermined optical characteristic of at least one of an illumination system (1-3, 6-8) for irradiating illumination light onto a to-be-detected subject and a detecting optical system (10, 9, 12, 15, 16, 21) for condensing a flux of light from the to-be-detected subject, is designed in such a way that forming first and second to-be-detected marks (HM1, HM2; 28A) on a substrate (11A) for evaluation in a predetermined positional relationship, forming third and fourth to-be-detected marks (HM3, HM4; 28B) which are the two to-be-detected marks rotated by a predetermined angle with the positional relationship maintained, measuring the relative positions of the first and second to-be-detected marks (HM1, HM2; 28A) on the substrate through the detecting optical system, measuring the relative positions of the third and fourth to-be-detected marks (HM3, HM4; 28B) on the substrate through the detecting optical system without rotating the substrate; and adjusts at least one of the illumination system and the detecting optical system based on the relative positions measured for the two sets of to-be-detected marks.
According to this invention, after the relative positions (e.g., the distance D1) of the first and second to-be-detected marks on the substrate are measured first, the relative positions (e.g., the distance D2) of the third and fourth to-be-detected marks on the substrate are measured without turning the substrate. As a result, for example, the TIS (Tool Induced Shift) which is a tool-caused error is (D1xe2x88x92D2)/2, and at least one of the illumination system and the detecting optical system is adjusted in such a way that this error falls within a predetermined allowable range. As the substrate need not be turned at this time, and if these two sets of to-be-detected marks have only to be sequentially placed in the observation view field of the detecting optical system, an ordinary stage which can perform two-dimensional positioning can be used, thus making it possible to measure the error in a short period of time with high precision.
In this case, as one example, at least one of the illumination system or the detecting optical system has only to be adjusted in such a way that the distance measured for the first and second to-be-detected marks becomes equal to the distance measured for the third and fourth to-be-detected marks. Accordingly, adjustment can be carried out in such a way as to substantially minimize the TIS.
As the first and second to-be-detected marks, a pair of box-in-box marks (28A) may be used. In this case, the TIS of, for example, an overlaying error measuring apparatus is measured.
A pair of lattice marks (HM1, HM2) each having recesses (33a, 35b) and projections (33b, 35a) alternately and periodically provided in a predetermined measuring direction and having such shapes that the recesses and the projections of one of the lattice marks are the inverse of those of the other one of the lattice marks, may be used as the first and second to-be-detected marks. In this case, it is possible to measure and adjust, with high precision, an error caused by, for example, misregistration of the center of the aperture stop of the illumination system.
A pair of lattice marks (DM1, DM2) each having recesses (31a, 32a) and projections (31b, 32b) provided at a predetermined pitch and having different ratios of the width of the recesses to the width of the projections, and thus different duty ratios which express the ratio of the width of the recesses (or projections) with respect to one pitch as percentages, may be used as the first and second to-be-detected marks. In this case, it is possible to measure and adjust an error originated from an asymmetrical aberration, such as coma, of the detecting optical system.
It is desirable that the third and fourth to-be-detected marks are the first and second to-be-detected marks rotated by 180xc2x0. Accordingly, the TIS as conventionally defined can be measured.
A first substrate (11A; 11B) for evaluation according to this invention, which has a plurality of to-be-detected marks formed thereon, is designed in such a way that the first and second to-be-detected marks (HM1, HM2, 28A; DM1, DM2) are formed in a predetermined positional relationship and the third and fourth to-be-detected marks (HM3, HM4, 28B; DM2, DM4) which are the two to-be-detected marks rotated by a predetermined angle with the same positional relationship are formed. By using this substrate, the adjusting method for an optical system according to this invention can be implemented.
A second substrate (11) for evaluation according to this invention, which has a plurality of to-be-detected marks formed thereon, is designed in such a way that at least two first to-be-detected marks (DM1, DM2) having recesses and projections alternately provided and having different ratios of the width of the recesses to the width of the projections are formed. By using this substrate, a position detecting apparatus can be adjusted with the aforementioned different ratio mark method.
As one example, this substrate is used in adjusting an optical apparatus which is to be incorporated in an apparatus which is used in a device fabricating process including a lithography process for transferring a device pattern onto a work piece (W) directly or through a mask (R). As one example, this substrate is substantially the same as a subject to be detected by the optical apparatus in shape and size, thus eliminating the need for newly producing a holder or the like.
A pattern detecting apparatus according to this invention, which is equipped with an illumination system (1-3, 6-8) that irradiates illumination light onto a to-be-detected subject through an objective optical system L10) and a detecting system (9, 12, 15, 16, 18, 21) that receives a flux of light which is generated from the to-be-detected subject and passes the objective optical system (10), comprises a movable member (11A) on which a pair of first marks (HM1, HM2) arranged along a first direction and a pair of second marks (HM3, HM4; 25Y) arranged along a second direction which crossing the first direction (including the case of turning the marks 180xc2x0) and having the same structure as the pair of first marks are provided integrally, and an adjusting mechanism (4a, 4b, 5a, 5b, 16a, 16b, 17a, 17b) which adjusts at least a part of the optical member (3, 16) in the illumination system, the objective optical system and the detecting system based on relative positional information acquired by detecting the pair of first marks through the objective optical system and relative positional information acquired by detecting the pair of second marks.
According to this pattern detecting apparatus, the adjusting method for an optical system according to this invention can be used. Further, it is possible to two-dimensionally adjust the optical characteristics.
A third adjusting method for a position detecting apparatus according to this invention, which is equipped with an illumination system (1-3, 6-8) for illuminating one to-be-detected mark or a plurality of to-be-detected marks and a detecting optical system (10, 9, 12, 15, 16, 21) for condensing a flux of light from the to-be-detected marks, for detecting the position of the one to-be-detected mark or relative positions of the plurality of to-be-detected marks based on the flux of light condensed by the detecting optical system., is designed in such a way that a substrate (11C) formed with an evaluation mark (DX, HX) having a center portion (DM22; HM22) comprised of a recess and projection pattern and two end portions (DM21, DM23; HM21, HM23) each having a recess and projection pattern arranged symmetrically in such a way as to sandwich the center portion in a predetermined measuring direction is placed in a to-be-detected area of the detecting optical system, and detecting the relative positional relationship (distance, dethroughtion or the like) of the center portion and the two end portions in the measuring direction through the detecting optical system, and adjusting a predetermined optical characteristic of the illumination system or the detecting optical system based on the measured value.
According to this invention, as one example, the distances between the center portion and both end portions of an evaluation mark are detected, and those distances are compared with a predetermined reference value (a true value) to determine the tool-induced error (TIS). At this time, a possible way of determining the reference value is to turn the evaluation mark 180xc2x0, remeasure the distances and take an average value of the results of the two measurements as the reference value. In this case, as the evaluation mark in this invention is symmetrical (line symmetrical) to the center portion in the measuring direction, the shape in the measuring direction is substantially the same even if the evaluation mark is turned 180xc2x0. Therefore, errors other than the tool-induced error, such as distortion, will not affect the measurement, and only the tool-induced error can be determined with high precision and thus that error can be corrected with high precision.
As one example, if the center portion and both end portions that constitute the evaluation mark are lattice marks with different ratios of the width of the recesses to the width of the projections (different ratio marks), it is possible to form the evaluation mark accurately and measure the image-forming optical state of the detecting optical system, particularly, an error in coma.
If the center portion and both end portions that constitute the evaluation mark are lattice marks whose recesses and projections are reversed (different step marks), it is possible to measure misregistration in the illumination state of the illumination system (misregistration of the illumination aperture stop, uneven illuminance distribution or the like) with high precision.
A third position detecting apparatus according to this invention, which is equipped with an illumination system (1-3, 6-8) that illuminates one to-be-detected mark or a plurality of to-be-detected marks, a detecting optical system (10, 9, 12, 15, 16, 21) that condenses a flux of light from the to-be-detected marks and a photoelectric detector (22) that receives the flux of light condensed by the detecting optical system, which detects a position of the one to-be-detected mark or relative positions of the plurality of to-be-detected marks based on a detection signal from the photoelectric detector, is designed in such a way that a positioning member, which is corrected at least a part of the optical member (3; 16) in the illumination system and the detecting optical system which affect a predetermined optical characteristic, and which positions the at least a pair of the optical member; and a control operation system (23), which is electrically connected to the photoelectric detector and the positioning member, and which drives the positioning member in order to reduce an error in the predetermined optical characteristics based on a relative positional relationship of at least three portions (DM21-DM23; HM21-HM23) of a predetermined evaluation mark to be detected through the detecting optical system and the photoelectric detector are provided. This apparatus can use the third adjusting method for a position detecting apparatus according to this invention.
In exposure system according to this invention, which has the aforementioned position detecting apparatus of this invention, a mask stage (54, 55) which holds a mask and a substrate stage (58, 59) which positions a substrate (W) onto which a pattern of the mask is to be transferred and on which an alignment mark for alignment is formed, are designed in such a way that positional information of the alignment mark on the substrate is detected by the position detecting apparatus and alignment of the mask with the substrate is carried out based on the detection result. A high degree of overlaying accuracy can be obtained by adjusting the optical system of the position detecting apparatus according to this invention by using the adjusting method of this invention.
A device manufacturing method according to this invention, which manufactures a predetermined device by using an adjusting method for the position detecting apparatus of this invention, includes the steps of adjusting a predetermined optical system in the position detecting apparatus by using the adjusting method, detecting positional information of an alignment mark on a predetermined substrate using the adjusted position detecting apparatus and aligning the substrate with a mask based on the detection result, and transferring a pattern of the mask onto the substrate. In this case, as high overlaying precision can be obtained, high-performance devices can be mass-produced with a high yield.
According to this invention, a method of manufacturing an exposure system which exposes a photosensitive substrate (W) with an energy beam through a mask (R) is such that providing a mark detecting system (63) which detects an alignment mark (38, 40X, 40Y) on the substrate, and the detecting system is provided in such a way that an optical axis is located outside an illumination area of the energy beam on a coordinate system where the substrate moves, and to detect a distance between at least two to-be-detected marks each having recesses and projections alternately provided with respect to an aligned direction, detecting the at least two to-be-detected marks by the mark detecting system, and moving or replacing at least one optical element in the mark detecting system based on the detected distance in order to adjust an optical characteristic of the mark detecting system.
In this case, the mark detecting system can be adjusted with high precision by using the adjusting method of this invention, such as the different ratio mark method, and high overlaying precision is obtained.
According to this invention, an adjusting method for an optical system in a position detecting apparatus having an illumination system for irradiating illumination light onto a to-be-detected subject and a detecting optical system for condensing a flux of light from the to-be-detected subject, adjusts a first optical characteristic of the illumination system, and adjusts a second optical characteristic of the detecting optical system after the adjustment of the first optical characteristic.
According to this invention, an exposure method in an exposure system equipped with the position detecting apparatus, which is a target for the adjusting method, is designed in such a way that an alignment mark formed on a substrate is detected by the position detecting apparatus adjusted by the adjusting method, the substrate is aligned based on the mark detection result, and a predetermined pattern is exposed on the aligned substrate.
Another position detecting apparatus according to this invention comprises an illumination system that irradiates illumination light onto a to-be-detected subject, a first adjusting unit that adjusts a first optical characteristic of the illumination system, a detecting optical system that condenses a flux of light from the to-be-detected subject, a second adjusting unit that adjusts a second optical characteristic of the detecting optical system, and a control unit that adjusts the second optical characteristic by the second adjusting unit after adjusting the first optical characteristic by the first adjusting unit.
Another exposure system according to this invention comprises another position detecting apparatus of this invention, and an alignment apparatus that detects an alignment mark formed on a substrate by using the position detecting apparatus adjusted by the first and second adjusting units and aligning the substrate based on the result of detection of the alignment mark, and exposes a predetermined pattern on the aligned substrate.